Aircraft undercarriages are known that include at least one axle having at least one wheel mounted to rotate thereon, the undercarriage including a communication device for connecting a sensor mounted on a rim of the wheel to stationary processor means mounted on the aircraft. In order to do this, the processor means are connected to a stationary antenna located at the end of the axle, while the sensor includes an antenna that enables the sensor to communicate without contact and by radio with the stationary antenna. Nevertheless, the end of the axle is generally protected by a metal cover secured to the wheel. In order to enable the two antennas to communicate, it is appropriate to fit the cover with a passive intermediate element that includes a radiative element facing the stationary antenna and a radiative element facing the antenna of the sensor.
In general, the stationary antenna extends all around the end of the axle, and the radiative element is circular and disposed facing the stationary antenna on the axis of the wheel, such that the facing stationary antenna and radiative elements interact electromagnetically in a manner that does not depend on the angular position of the wheel. All of the radiation from the stationary antenna influences the facing radiative element.